This phase II study examined a regimen (FOLFOX7) of leucovorin (LV), high-dose intensity oxaliplatin, and 5-fluorouracil (5-FU), as second-line therapy for metastatic colorectal cancer. 48 patients were enrolled - 36 refractory and 12 resistant to prior therapy with LV-5-FU. Oxaliplatin (130 mg/m2) was infused with LV (400 mg/m2) over 2 h on day 1, followed by bolus 400 mg/m2 and a 46-h infusion (2400 g/m2) of 5-FU, every 2 weeks. Patients who responded or were stable received eight cycles. Patients were evaluated every 2 months. 20 patients (42%) had partial responses (95% confidence interval (CI): 28-56%), 19 (40%) had stable disease and 9 (19%) progressed. Median progression-free survival (PFS) was 6 months and median survival 16.1 months. Toxic effects of National Cancer Institute-Common Toxicity Criteria (NCI-CTC) grade 3/4 were: peripheral neuropathy 15%, nausea 8%, diarrhoea 11%, neutropenia 9%, thrombocytopenia 11%. Overall, 38% of patients experienced grade 3/4 toxicities, and 64% received 90% or more of the scheduled oxaliplatin dose intensity during the first four cycles. FOLFOX7 was highly active, with good tolerability, in pretreated patients resistant to LV-5-FU [corrected].